Is it possible

Hi
I think I may have been set an impossible task; by my boss.
We are using outlook express 5 on an easy mail server. i need to find a way of dumping 15 mails on to the server so that all users get the emails.
Unfortunately I do not know all theuser names.

Is there any quick way of getting these emails on the server other than sending then as the anti spamming software keeps blocking me?

I would be grateful for any help.

Simon